This invention relates to a composition comprising MAg4I5, wherein M is a monovalent cation, in the form of anisotropic crystalline particles; a process for preparing MAg4I5; an emulsion comprising MAg4I5 in an organic solvent, a photothermographic element comprising an emulsion layer comprising MAg4I5 in the form of anisotropic particles; and a method of forming a stable aqueous dispersion of MAg4I5.
MAg4I5 (wherein M is a monovalent cation) is a high ionic conductivity solid electrolyte. Conventional MAg4I5 preparation methodology involves the dissolution of MI in molten AgI. Stoichiometric amounts of MI and AgI are ground then melted in an alumina crucible above 560xc2x0 C., in flowing argon, then cooled to room temperature. The resulting ingot is then ground by ball milling for several hours to produce MAg4I5 in powder form.
Commonly assigned, copending application Ser. No. 08/939,465, filed Sep. 29, 1997, now abandoned, discloses an AgI based photothermographic imaging system that utilizes the controlled decomposition of MAg4I5 in acetone as the process to generate an imaging material. The MAg4I5 reagent disclosed in the ""465 application is generated by the above described conventional preparation methodology. This process requires high temperatures and numerous process steps. It would be desirable to produce the MAg4I5 by a simpler method.
As discussed in the ""465 application, MAg4I5 can be used to generate light sensitive AgI for use in a photothermographic element. In preparing photothernographic elements as described in the ""465 application, an organic solvent is used for forming the light sensitive imaging layer. It would be desirable to be able to use water as the solvent in preparing a photothermographic element. However, MAg4I5 is unstable in water. It would be desirable to provide a stable aqueous composition containing MAg4I5.
It is desirable to provide a simpler method of preparing MAg4I5 without high-temperature processing or ball milling. It would also be desirable to prepare MAg4I5 dispersed in an organic solvent medium, which may contain a binder, for use in preparing an imaging layer of a photothermographic element. It is also desirable to prepare MAg4I5 in powder form which can be directly dispersed in an organic solvent. Further, it would be desirable to provide a stable aqueous composition comprising MAg4I5 for a variety of uses including use in a photographic or photothermographic element.
One aspect of this invention comprises a composition comprising MAg4I5, wherein M is a monovalent cation, in the form of anisotropic crystalline particles.
Another aspect of this invention comprises a process for generating particles of MAg4I5, wherein M is a monovalent cation, which comprises dissolving AgI and MI in a polar solvent followed by precipitating particles of MAg4I5 by adding the solution to a nonpolar solvent.
Yet another aspect of this invention comprises an emulsion comprising MAg4I5, wherein M is a monovalent cation, in an organic solvent.
Still another aspect of this invention comprises a photothermographic element containing at least one emulsion layer comprising MAg4I5, wherein M is a monovalent cation, in the form of anisotropic crystalline particles.
A further aspect of this invention comprises a method for preparing a stable aqueous emulsion of MAg4I5, wherein M is a monovalent cation, which method comprises forming a saturated solution of water and a solute and then adding MAg4I5 to the saturated solution.
This invention provides:
(1) anisotropic crystalline particles of MAg4I5, where M is a monovalent cation;
(2) an alternative to high temperature processing to make MAg4I5, where is a monovalent cation;
(3) a method of precipitating MAg4I5, where M is a monovalent cation, articles in organic solvent;
(4) a method of forming fine particles of MAg4I5, where M is a monovalent cation, without ball milling;
(5) a procedure for stabilizing fine particles of MAg4I5, where M is a monovalent cation, in aqueous environments; and
(6) a photothermographic element containing anisotropic crystalline particles of MAg4I5.